Contactless identification systems or radio-frequency identification (RFID) systems may include a base station and one or more transponders or remote sensors. In an active transponder system the base station and transponder each have their own power supply. Moreover, in the active transponder system, the transponder may have an active transponder for data transmission to the base station. In a passive transponder system, the transponders do not have their own power supply or an active transmitter for data transmission to the base station. Passive transponders may draw power necessary for their operation from an electromagnetic field emitted by the base station.
In a RFID system, data may be wirelessly exchanged between the base station and associated transponders. The data exchange between the transponder and base station may be in response to a signal from the base station after an authentication procedure. In certain cases, the authentication procedure may be initiated without prompting from a user through re-transmission of signals between the transponder and base station. Data exchanged between the transponder and base station may include information to identify the transponder to the base station or initiate a function of a device.